Flying bodies such as cruise missiles equipped with their own propulsion plant that becomes effective after launching the cruise missile, are also equipped with means for an autonomous target acquisition and homing toward that target. These means conventionally employ radar altitude meters including lidar or sonar systems or inertial guidance systems. These conventional systems have their problems, especially when the missile traverses a hilly topography at a low altitude.
A low altitude, topography hugging radar is known from German Patent Publication (DE-OS) No. 3,417,073. However, that system operates on the basis of previously stored topographic data which requires a large computer effort and expense.
German Patent Publication (DE-PS) No. 3,016,554 discloses an orientation system operating with the pulse-doppler radar principle. Such systems are carried on board of aircraft. Such system enables an observer to see the topography relative to which the aircraft is flying, independently of any optical visibility which may be obscured by an obstacle or the like. The system employs radar technology to make the topography visible, whereby two rod-type antennas are used to acquire the necessary data with the pulse doppler radar principle to provide the required perspective illustration of a topography section. The improvement provided by the system of German Patent Publication No. 3,016,554 resides in the fact that a two-dimensional map is converted into a three-dimensional image on a radar screen. However, the known system has the disadvantage that the information density of data to be supplied to the on-board computer per unit of time is so high that it must be limited in order to avoid overloading the abilities of the on-board computer.